A terminal block assembly includes an actuator member that is displaceable relative to a terminal block to transport an insulated conductor into engagement with the knife edges of a stationary electrical contact on the terminal block, thereby to effect penetration of the insulation and electrical connection between the conductor and the stationary contact, characterized by the provision of a U-shaped support spring having leg portions between which the stationary contact is supported.
A terminal block with a connecting device that penetrates the insulation layer of an insulated conductor is disclosed in the German published application No. 196 27 209. The connecting device illustrated in this publication features contact cutters with cutting edges that widen to form contacting surfaces. The contacting surfaces facilitate a larger-surface contacting of the line lead(s) of the connected electrical conductor than do the actual contact cutters used in severing the conductor, which essentially touch the conductor in a xe2x80x9clinear fashion.xe2x80x9d
The solution offered in German Patent No. DE 197 32 182 C1 proved effective in order further to support the outside resiliency of the connecting devices. This publication discloses, among other things, a cutting terminal contact with a contact spring having two elastic contact legs that define a contact slit where a U-shaped support spring is provided that has plate-shaped spring legs. The U-shaped support spring or overspring is designed as a part that is separated from the actual contact or the resilient contact. The plate-shaped spring legs essentially are aligned normal to the cutting terminal or the contacting areas of the contact legs and encompass the latter along the contact slit over a predetermined width.
European Patent No. EP 0 936 697 A1 discloses a typical terminal block. The contact springs are made each time on both ends of a bus bar, which is so aligned in the housing made of insulation material that the insertion openings of the two resilient stationary contacts point away from each other, that is to say, a conductor is introduced into the resilient contact from the outside with relation to the mounting rail. To make the actual introduction of the conductors into the contact springs easier, there are provided contact activation pieces that are arranged on the top of the housing that is made of insulation material. The contact activation pieces are made in the form of a slide and are inserted in the housing made of insulation material from the outside upon first assembly. Each has a conductor introduction opening, and under an essentially U-shaped recess in the foot area, it has lateral catch surfaces as well as a deep stop for the conductor.
Dovetail-like guides are made in the upper opening area of the housing made of insulation material; the contact activation piece is guided in a movable manner on these guides with bilaterally corresponding dovetail grooves. The contact activation piece can be shifted by means of a screwdriver between a conductor insertion position and a contacting position and these two positions are defined by a catch position.
This terminal block and its connecting devices generally have proven to be effective. For various practical purposes, however, it is desirable to so develop the design structure of the terminal block and the connecting device that one can make terminal blocks with particularly small dimensions. In particular, the dimensions of the metal subassembly of the connecting device should be made as compact as possible, and the forces that are introduced into the insulation material housing of the terminal block should also be kept as small as possible. The task of the present invention is to solve this problem.
Accordingly, a primary object of the present invention is to provide a terminal block assembly including a U-shaped support spring have leg portions that extend on opposite sides of the stationary electrical contact to support the same during the displacement of an insulated conductor by an activator member toward and away from the insulation-severing knife edges of the stationary contact. In this manner, the stationary contact is supported within the terminal block housing against the forces applied thereto during the severing of the conductor insulation by the knife edges.
According to another object of the invention, in one embodiment, the bus bar extends through the U-shaped support spring adjacent the lower base portion thereof. The bus bar then extends upwardly and is reversely bent back inwardly over the bus bar with the stationary spring contact being supported between the upper ends of the leg portions of the support spring. In another embodiment, the bus bar extends in supporting relation under the base portion of the support spring, and a second bus bar section carries the reversely bent portion that supports the stationary resilient contact between the upper ends of the leg portions of the U-shaped support spring.
According to a further object of the invention, the actuator member that displaces the insulated conductor toward and away from the knife edges of the stationary contact are guided by guide pin and groove means for pivotal or linear movement relative to the terminal block housing. The guide pins extend laterally from the actuator for engagement with the guide grooves contained in opposing walls of the terminal block. Both the actuator member and the terminal block are formed from electrically insulating synthetic plastic material. The guide means prevent jamming of the actuator relative to the terminal block, and the length of the guide grooves may be reduced as compared with a pure shifting of the actuator member without any guide means.
Another object of the invention is to arrange the stationary resilient contacts on inwardly directed end portions of the bus bar, with the respective actuator members being arranged between the stationary contacts. In this manner, only pressure forces act on the actuator members during the displacement thereof between their engaged and disengaged portions relative to the stationary contacts.
A further object of the invention is to provide the stationary contacts with lateral recesses for receiving the upper ends of the support springs, and to provide the support spring legs with notches for receiving corresponding shoulders of the stationary contacts.